To prevent leakage and failure in flanged piping systems, flange sealing gaskets are used between pipe segments and are also used in the flanged connections for valves, other piping fixtures, and vessels. The most common type of piping flange used in plant and other applications is a raised face flange. The face of the raised face-type flange has an inner circular gasket contacting surface which is raised above (i.e., projects outwardly with respect to) a surrounding outer bolting circle. Depending upon the pressure classification of the flange, the projecting height of the raised face will typically be about 1.6 mm ( 1/16 inch) or 6.4 mm (¼ inch). The purpose of the raised face is to concentrate more pressure on a smaller gasket area and thereby increase the pressure containment capability of the flanged joint.
Raised face flanges accommodate the use of a wide variety of gasket designs. Examples of such gasket designs include, but are not limited to, flat ring sheet gaskets, spiral wound gaskets, gaskets with circular face serrations, and double jacketed gaskets. Many gaskets include (a) a circular inner portion which is spiral wound, serrated, or otherwise formed for sealing contact and has a radial width which is preferably substantially equal to or slightly greater than the radial width of the raised face of the flange and (b) an outer circular portion which surrounds that circular inner portion of the gasket and fits within the bolt circle of the flange when installed.
Although flange gaskets often represent a minor portion of the overall cost of a piping system, the consequences of a gasket failure can sometimes include fires, explosions, releases of hazardous chemicals, and/or other catastrophes. Such catastrophic failures can result in significant repair costs, lost production, fines, downtime, damage to the environment, and even death or serious personal injury.
Unfortunately, flange gaskets are difficult to manage and hold in place when joining pipe segments, installing valves, etc. Workers attempting to hold the gaskets in place by hand can be seriously injured. In this same regard, the gaskets themselves can also be easily scratched, gouged, or dented, for example, when accidentally impacted by tools or when subjected to collisions which can occur when attempting to position and align mating flanges using cables and rigging or by other means.
When the gasket is damaged in this manner, it must often be discarded and replaced, thus slowing and increasing the cost of the installation process. Moreover, in many cases such damage is not observed or is otherwise missed during installation and may result in leakage or catastrophic failure.
In an attempt to protect workers from injuries and to better align and protect the flange gaskets, caulks, glues or other substances are sometimes used to hold flange gaskets in place during the installation process. However, these substances can also damage the gasket or cause other problems which may result in gasket failure. For example, caulks and other substances often contain acidic components or other materials which are not compatible with the gasket and can cause the gasket to corrode over time. Also, because of their lubricity, caulks and other substances can cause the gasket to shift within the flange if contacted, pushed, or squeezed during installation or during the bolt tightening process. Glues, on the other hand, require significant time to apply and dry properly and can interfere with sealing effectiveness of the gasket.
As will therefore be apparent, a need currently exists for a more effective means of retaining a flange gasket when joining pipe segments, installing valves, attaching lines to vessels, etc. The improved means for retaining the flange gasket will preferably be hands free and will also preferably: (a) prevent worker injuries, (b) protect the gasket from damaging impacts and collisions, (c) accelerate the installation process, (d) eliminate the need to apply caulks, glues, or other substances, and (e) ensure that the positioning and alignment of the gasket flange are properly and precisely maintained during installation.